Method of operating a vacuum corrugated belt feeder to improve sheet acquisition from a feed supply

ABSTRACT

A method of operating a vacuum corrugated belt feeder during a feed cycle wherein the paper is taken away by a belt which is activated when a feed clutch is energized, and wherein the vacuum is actuated at the start of the feed cycle and de-actuated prior to, or at the same time as the feed clutch is de-energized. According to an aspect of the invention the improvement comprises pulsing the positive air pressure separator by actuating and de-actuating the positive air pressure separator during the feed cycle, and pulsing the high pressure separator by actuating and de-actuating the high pressure separator during the feed cycle.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a 111A application of Provisional Application Ser. No. 60/557,512, filed Mar. 29, 2004, entitled METHOD OF OPERATING A VACUUM CORRUGATED BELT FEEDER TO IMPROVE SHEET ACQUISTION FROM A FEED SUPPLY by Michael T. Dobbertin, et al.

BACKGROUND

The present invention is in the field of printers and copiers. More specifically this invention relates to a receiver sheet supply and feed apparatus, including a vacuum corrugated feeder, and which may have a positive air pressure separator on such printers and copiers. This invention is useful for the apparatus described by the U.S. Pat. No. 5,344,133 “Vacuum belt feeder having a positive air pressure separator and method of using a vacuum belt feeder” by Jantsch et al, which patent is hereby incorporated by reference in its entirety. The incorporated patent refers to a vacuum, a first positive air supply, and a second positive air supply. The first and second positive air supplies are used simultaneously and will herein be referred to collectively as the airknife.

The present invention is further useful for the apparatus described by the U.S. Pat. No. 6,629,692 B2 “Device for Separating an Uppermost Sheet from a Supply Stack by Means of Air Blowers” by Allner et al, which patent is hereby incorporated by reference in its entirety. The incorporated patent refers to a vacuum, a first positive air supply, and a second air supply, wherein one of the positive air supplies is from a pressurized source.

In typical reproduction apparatus such as copiers or printers, information is reproduced on individual cut sheets of receiver material such as plain bond paper or transparencies. Such receiver sheets are stored in a stack and fed individually when copies are to be produced. The sheet feeder for the reproduction apparatus must be able to handle a wide range of sheet types and sizes reliably and without damage. Sheets must be fed individually, without misfeeds or multi-feeds.

The vacuum belt feeder described in the incorporated patent is useful for separating the top sheet from a sheet supply stack when the stack is a bond, cover, index, recycled, or other relatively rough, uncoated papers. Coated paper is frequently used in the offset printing market due to its improved print quality for that purpose. These papers are generally considerably smoother than the uncoated papers. Color prints, either printed on a color digital printer or by adding digital monochrome print over color offset shells, are quickly gaining in popularity. Thus, the use of smoother papers in electrophotographic printers is becoming much more common.

The smoothness of the paper makes it difficult to get air between the sheets to allow the top sheet to be separated from the rest of the stack. It is also more difficult to separate the top sheets when the paper is a heavier paper, or when the paper is prepunched.

A method of operating a vacuum corrugated belt feeder is desired which would allow for reliable separation even when the paper is a coated or a heavier weight paper, or is prepunched.

SUMMARY OF THE INVENTION

A method of operating a vacuum corrugated belt feeder during a feed cycle wherein the paper is taken away by a belt which is activated when a feed clutch is energized, and wherein the vacuum is actuated at the start of the feed cycle and de-actuated prior to, or at the same time as the feed clutch is de-energized. According to an aspect of the invention the improvement comprises pulsing the positive air pressure separator by actuating and de-actuating the positive air pressure separator during the feed cycle, and pulsing the high pressure separator by actuating and de-actuating the high pressure separator during the feed cycle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a receiver sheet supply and feeding apparatus.

FIG. 2 is a top plan view of a receiver sheet supply and feeding apparatus of FIG. 1 with portions removed or broken away to facilitate viewing FIG. 3 is a side view of a cross-section of a receiver sheet supply and feeding apparatus taken along lines 3-3 of FIG. 2.

FIG. 4 is a side cross-sectional view of a portion of a receiver sheet supply and feeding apparatus,

FIG. 5 is an end view of a portion of the receiver sheet supply and feeding apparatus, taken along the lines 5-5 of FIG. 3.

FIG. 6 is an end view of a portion of the receiver sheet supply and feeding apparatus, taken along the lines 6-6 of FIG. 3.

FIG. 7 is a timing chart for operation of a receiver sheet supply and feeding apparatus with 8.5″×11″ receiver paper, according to an aspect of the invention.

FIG. 8 is a timing chart for operation of a receiver sheet supply and feeding apparatus with 11″×17″ receiver paper, according to an aspect of the invention.

FIG. 9 is a timing chart for operation of a receiver sheet supply and feeding apparatus with 11″×17″ receiver paper, according to an aspect of the invention.

DETAILED DESCRIPTION

Following is a detailed description of the drawings which show the vacuum belt feeder with positive air pressure separator as described in U.S. Pat. No. 6,629,692. Although this system is described in detail, the present invention is not limited to use in this particular system. Any printer/copier which uses a combination of vacuum, positive air pressure and a high pressure air source to lift and separate the top sheets from a feed stack may make use of this invention.

The detailed description is written to a top feed vacuum corrugated feed device, but the present invention is also useful for a bottom feed vacuum belt feed device. In the case of a bottom feed device, instead of separating the top sheet, the vacuum, airknife and high pressure separator would be separating the bottom sheet.

Various aspects of the invention are presented in FIGS. 1-9 which are not drawn to scale and in which like components are numbered alike. Referring now to FIGS. 1-2, a receiver sheet supply and feeding apparatus are shown. The receiver sheet supply and feeding apparatus designated generally by the numeral 10, includes an open hopper 12 and an elevating platform 14 for supporting a stack of sheets. A sheet stack 15 supported on the platform 14 contains individual sheets suitable for serving as receiver sheets for having reproductions formed thereon in a copier or printer device.

The sheet stack-supporting platform 14 is supported within the hopper 12 for substantially vertical elevational movement by a lifting mechanism. The lifting mechanism serves to raise the platform 14 to an elevation for maintaining the topmost sheet in the stack at a predetermined level during operation. Maintaining the topmost sheet at the predetermined level is accomplished by a sheet detection switch 80 (see FIG. 5), or multiple switches, which controls the operation of a motor for actuating the lifting mechanism to raise the platform until a switch or switches is activated.

A sheet feed head assembly 30 is located in association with the hopper 12 so as to extend over a portion of the platform 14 in spaced relation to a sheet stack 15 supported thereon. The sheet feed head assembly 30 includes a ported plenum 32 connected to a vacuum source 31, and an airknife 40 connected to a positive pressure air source 41. A positive pressure airjet from the airknife 40 levitates the top sheets in the supported sheet stack 15. Vacuum at the plenum 32 is effective through the plenum ports 33 to cause the topmost levitated sheet from the stack to thereafter be acquired at the plenum 32 for separation from the sheet stack 15. This adheres the topmost sheet to the belt 36 via the belt ports 37. Additional positive air pressure jets 44 from the airknife 40 assure separation of subsequent sheets from the acquired topmost sheet.

A vacuum valve 38 (see FIG. 5) is used to control the operation of the vacuum. Thus during a feed cycle, the valve will be open so as to levitate the top sheet in the stack. In a preferred method of operation, the opening and closing of the vacuum valve is timing based, however, valve operation may also be controlled by other methods, such as a pressure or a mechanically activated switch. For example, a switch may be attached to the plenum 32 to detect when a sheet has been acquired. A signal provided by the switch on detection of sheet acquisition may be utilized to control operation of various components of the sheet feed head assembly 30, such as timing of activations or setting of air flow levels, to optimize operation for a particular type (size) of sheet to be fed from the sheet supply and feeding mechanism 10. When the vacuum is said to be “actuated”, this means that the vacuum valve 38 is open. When the vacuum is said to be “de-actuated” this means that the vacuum valve 38 is closed.

The airknife 40 comprises a first air jet arrangement 42 and a second air jet arrangement 44. The first air jet arrangement incorporates a single nozzle 43 in fluid communication with a source of positive pressure air 41, for example a range of 4-10 inwg (inches of water) in certain embodiments. The chambers which are part of the first air jet arrangement 42 and the second air jet arrangement 44 may be separate chambers, or may be combined into one larger chamber. The nozzle 43 directs a positive pressure air stream at the sheet stack, in the center of the lead edge, to fluff the top sheets in the stack to bring the topmost sheet into association with the sheet feed head assembly 30 where it can be acquired by vacuum, at the plenum 32.

The second air jet arrangement 44 incorporates a plurality of nozzles 46 in fluid communication with the source of positive pressure air 41. The nozzles 46 are aimed slightly above the aim point for the first air jet nozzle 43. The purpose of the second air jet arrangement 44 is to separate any sheets adhering to the topmost sheet acquired by the sheet feed head assembly 30.

A positive pressure air valve 60 is used to control the flow of positive pressure air through the airknife 40. When the positive air pressure separator 40 is actuated, this means the positive air pressure valve 60 is open. When the positive air pressure separator 40 is de-actuated, this means the positive air pressure valve 60 is closed. However, when the positive air pressure valve 60 is closed, that does not necessarily mean that there is no positive pressure airflow. In a preferred design, the positive air pressure valve 60 allows some airflow even when closed (does not close all the way). One commonly used valve design allows about one third of the airflow through an open valve to flow through when the valve is ‘closed’.

The high pressure separator 70 comprises a high pressure jet arrangement 72 in fluid communication with a high pressure air source 74. The high pressure air source is at least 5 psi, and typically on the order of 5-30 psi. A high pressure air valve 76 is used to control the flow of high pressure air. When the high pressure separator 70 is actuated, this means the air pressure valve 76 is open. When the high pressure separator 70 is de-actuated, this means the high pressure air valve 76 is closed.

A method of operating a vacuum corrugated belt feeder during a feed cycle wherein the paper is taken away by a belt 36 which is activated when a feed clutch is energized, and wherein the vacuum is actuated at the start of the feed cycle and de-actuated prior to, or at the same time as the feed clutch is de-energized. According to an aspect of the invention the improvement comprises pulsing the positive air pressure separator 40 by actuating and de-actuating the positive air pressure separator 40 during the feed cycle, and pulsing the high pressure separator 70 by actuating and de-actuating the high pressure separator 70 during the feed cycle.

According to a further aspect of the invention, the positive air pressure separator 40 and the high pressure separator 70 are actuated prior to or when the vacuum is actuated, and the positive air pressure separator 40 and the high pressure separator 70 are de-actuated before the feed clutch is energized.

In a preferred embodiment of the invention, when the feed rate is in the range of 110-150 pages per minute, the positive air pressure separator 40 and the high pressure separator 70 are actuated when the vacuum is actuated, and the positive air pressure separator 40 and the high pressure separator 70 are de-actuated approximately 50 milliseconds before the feed clutch is energized.

According to a further aspect of the invention, the high pressure separator 70 may be manually deactivated. In a further preferred embodiment of the invention, the high pressure separator 70 is automatically deactivated based on predetermined criteria. For instance, pulsing of high pressure air is not desirable for non-continuous trail edge paper such as tabstock, and if such paper is detected, the high pressure air should be deactivated.

FIG. 7 is a timing chart showing how the timing of the various operations interact, according to an aspect of the invention.

According to an aspect of the invention a method of operating a vacuum corrugated belt feeder feeding specialized paper sheets pulses the positive air pressure separator 40 by actuating and de-actuating the positive air pressure separator 40 during the feed cycle, and pulses the high pressure separator 70 by actuating and de-actuating the high pressure separator 70 during the feed cycle.

This method is especially useful when the specialized paper is a smoother paper such as a coated paper, when the paper is of a heavier weight, such as heavier than 200 gsm (grams per square meter), or when the paper is prepunched.

When using large format receivers (e.g. 11×17), duplex printing, or multiple supplies (e.g. body paper, covers and inserts) there are image frames in which no feed is required from a given supply. There is an opportunity to use this time to improve the feed reliability of the next sheet to be fed from that supply. In U.S. Pat. No. 6,554,269, “Airknife and Vacuum Control Changes to Improve Sheet Acquisition for a Vacuum Corrugated Feed Supply” by Dobbertin et al, which patent is hereby incorporated by reference in its entirety, a method is disclosed for making use of the non-feed cycle time by ‘fluffing’ the top sheet in the sheet supply stack by actuating the vacuum or the vacuum and airknife during this time. According to a further aspect of the invention, pulsing of a high pressure separator 70 during non-feed cycle time is also useful to improve feed reliability. Thus a method for operating a vacuum corrugated belt feeder during non-feed cycle time comprises agitating the top sheets in a stack by actuating the vacuum 38, and pulsing the high pressure separator 70 and the positive air pressure separator 40.

In a preferred embodiment of the invention, the high pressure separator 70 and the positive air pressure separator 40 remain actuated until the feed cycle begins. In a further preferred embodiment, the vacuum 38, the high pressure separator 70, and the positive air pressure separator 40 are actuated and de-actuated every frame as if supply were feeding.

According to further aspect of the invention, during non-feed cycle time the vacuum 38, the high pressure separator 70, and the positive air pressure separator 40 are actuated for the frame immediately following the last feed, de-actuated, and then not actuated again until the feed cycle begins.

In a further aspect of the invention, the vacuum, the high pressure separator 70, and the positive air pressure separator 40 are actuated at least one frame during non-feed cycle time, but not every frame. In a preferred embodiment the impending feed is identified, and the vacuum, the high pressure separator 70, and the positive air pressure separator 40 are actuated during the last frame before the impending feed begins.

The “fluffing” (which is referred to as “warm-up cycle” in FIGS. 7-9) as described above is done during the non-feed cycle time, because there is not enough time during the feed cycle. A standard 8.5″×11″ sheet takes 1 ‘frame’ (the start of which is referred to as “F perf”, standing for frame perforation, in FIGS. 7-9) to acquire and feed, and one ‘frame’ to image. Thus the next sheet is being acquired and fed while a previous sheet is being imaged. However, when the paper is longer, for example 11″×17″, it takes longer than 1 standard ‘frame’ to feed, but less than 2 ‘frames’, while it takes 2 ‘frames’ to image the paper. Thus the difference between the time it takes to acquire and feed a longer sheet, and the time it takes to image the longer sheet is “down time”. This time may be used as it is used above in the non-feed cycle time, by “fluffing” the paper to prepare for acquisition. According to an aspect of the invention, when the vacuum corrugated belt feeder is feeding longer sheets, such as 11″×17″, a method of operation additionally comprises pulsing the vacuum 38, the high pressure separator 70, and the positive air pressure separator 40 during this down time. This is shown in the timing chart of FIG. 8. FIG. 9 is a timing chart for operation of a receiver sheet supply and feeding apparatus with 11″×17″ paper, in duplex mode, according to an aspect of the invention. 

1. In a vacuum corrugated belt feeder with a positive air pressure separator and a high pressure separator, a method of operating a vacuum corrugated belt feeder during a feed cycle wherein said vacuum, said positive pressure air, and said high pressure air are controlled by a vacuum valve, a positive air pressure valve, and a high pressure valve respectively, wherein the paper is taken away by a belt which is activated when a feed clutch is energized, wherein the vacuum is actuated at the start of the feed cycle and de-actuated prior to, or at the same time as the feed clutch is de-energized, the improvement comprising: pulsing the positive air pressure separator by actuating and de-actuating said positive air pressure separator during the feed cycle; and, pulsing the high pressure separator by actuating and de-actuating said high pressure separator during the feed cycle.
 2. The method of claim 1 wherein said positive air pressure separator and said high pressure separator are actuated prior to or when said vacuum is actuated, and said positive air pressure separator and said high pressure separator are de-actuated before the feed clutch is energized.
 3. The method of claim 1 when the feed rate is in the range of 110-150 pages per minute, wherein said positive air pressure separator and said high pressure separator are actuated when said vacuum is actuated, and said positive air pressure and said high pressure separator are de-actuated approximately 50 milliseconds before the feed clutch is energized.
 4. The method of claim 1 wherein said high pressure separator may be manually deactivated.
 5. The method of claim 1 wherein said high pressure separator is automatically deactivated based on predetermined criteria.
 6. In a vacuum corrugated belt feeder with a positive air pressure separator and a high pressure separator, a method of operating a vacuum corrugated belt feeder feeding specialized paper sheets during a feed cycle wherein said vacuum, said positive pressure air, and said high pressure air are controlled by a vacuum valve, a positive air pressure valve, and a high pressure valve respectively, wherein the paper is taken away by a belt which is activated when a feed clutch is energized, wherein the vacuum is actuated at the start of the feed cycle and de-actuated when the feed clutch is de-energized, the improvement comprising: pulsing the positive air pressure separator by actuating and de-actuating said positive air pressure separator during the feed cycle; and, pulsing the high pressure separator by actuating and de-actuating said high pressure separator during the feed cycle.
 7. The method of claim 6 wherein said specialized paper is coated paper.
 8. The method of claim 6 wherein said specialized paper is paper heavier than 200 gsm.
 9. The method of claim 6 wherein said positive air pressure separator and said high pressure separator are actuated when said vacuum is actuated, and said positive air pressure separator and said high pressure separator are de-actuated before the feed clutch is energized.
 10. The method of claim 6 when the feed rate is in the range of 110-150 pages per minute, wherein said positive air pressure separator and said high pressure separator are actuated when said vacuum is actuated, and said positive air pressure and said high pressure separator are de-actuated approximately 50 milliseconds before the feed clutch is energized.
 11. In a vacuum corrugated belt feeder with a positive air pressure separator and a high pressure separator, a method of operating a vacuum corrugated belt feeder during non-feed cycle time so as to separate a sheet from a sheet supply stack, comprising agitating the top sheets in the stack by actuating said vacuum, and pulsing said high pressure separator and said positive air pressure separator.
 12. The method of claim 11 wherein said vacuum and said high pressure separator and said positive air pressure separator remain actuated until the feed cycle begins.
 13. The method of claim 11 wherein said vacuum and said high pressure separator and said positive air pressure separator are actuated and de-actuated every frame as if supply were feeding.
 14. The method of claim 11 wherein said vacuum and said high pressure separator and said positive air pressure separator are actuated for the frame immediately following the last feed, de-actuated, and then not actuated again until the feed cycle begins.
 15. The method of claim 11 wherein said vacuum and said high pressure separator and said positive air pressure separator are actuated at least one frame during non-feed cycle time, but not every frame.
 16. The method of claim 11 wherein the impending feed is identified, and said vacuum and said high pressure separator and said positive air pressure separator are actuated during the last frame before the impending feed begins.
 17. In a vacuum corrugated belt feeder with a positive air pressure separator and a high pressure separator, a method of operating a vacuum corrugated belt feeder, feeding a sheet too large to image in one frame, during feed cycle time comprises pulsing the vacuum, the high pressure separator, and the positive air pressure separator after a previous sheet has been fed, but before a next sheet is fed. 